Methods for oxidatively ireating flour



y 1961 c. G.'FERRARI ET AL 2,992,923

METHODS FOR OXIDATIVELY TREATING FLOUR Filed June 25, 1959 3 50 a 40"flip/M, 4 Q E Q .30 ii u 20 s g /0 kl /2.4 .66 7'69/0///2 F/G. W5 WFIG. 2 77/145 (Om/5) INVENTORS CHARLES G. F 52/242! KAzuo H/GASH/UcH/ATTORNEY United States Patent C) r 2,992,923 METHODS FOR 'OXIDATIVELYTREATING FLOUR Charles G. Ferrari, Evanston, and Kazuo Higashiuchi,

Chicago, 111., assignors to J. R. Short Milling Company, Chicago, 111.,a corporation of Illinois Filed June 23, 1959, Ser. No. 822,225

8 'Claims. (Cl. 99-91) This invention relates to the treatment of cerealflours and particularly to an improved process for oxidatively treatingflours to accomplish bleaching and/or maturing thereof.

Both maturing and bleaching of flours result from oxidative changes inthe flour. Maturing can be considered as the same oxidative change whichwould result from natural aging of the flour .for a prolonged period,while bleaching results from the more or less complete oxidation of thecarotinoid pigments of the flour to colorless reaction products.Numerous oxidizing agents have been proposed for maturing and bleachingflours. Of these prior art agents, most have been useful to accomplishonly maturing or only bleaching. Thus, the bromates, the iodates and thepersulfates, all accepted maturing agents, have no bleaching power.Conversely, benzoyl peroxide, one of the more commonly acceptedbleaching agents, has no maturing power. The only known agent acceptedfor 2 bleaching and maturing action than do the reaction productmixtures as a whole.

The present invention is based upon the discovery that reaction productmixtures derived from methyl ethyl ketone and hydrogen peroxide aremarkedly superior to any of the aforementioned peroxidic acetone andhydrogen peroxide.

The flour-treating method of the present invention employs oxidativelyactive materials obtained by combining methyl ethyl ketone, hydrogenperoxide and water in proportions providing in the initial reactionmixture from .5 to 2.5 moles of hydrogen peroxide for each' mole ofmethyl ethyl ketone and maintaining the resulting initially homogeneousreaction mixture at below 100 C. until, upon standing at normaltemperatures, the reaction mixture separates into phases of difierentspecific gravity, the phase of lower specific gravity predominantlycomprising methyl ethyl ketone peroxide and free methyl ethyl ketone.Advantageously, an acid catalyst is employed i-n proportions up to 5% byweight of the reaction products derived from .mixture to accelerateformation of the peroxidic product desired. Depending upon the relativeproportions of methyl ethyl ketone and hydrogen peroxide, the amount ofwater introduced into the reaction mixture with the hydrogen peroxide orotherwise, the temperature at which I the reaction mixture ismaintained, and whether or not commercial use and capable of bothmaturing and bleaching flours is chlorine dioxide. Chlorine dioxide has,how ever, proved to be disadvantageous'in several respects, the primarydisadvantage being that it is too potent, so that an unduly criticalcontrol of the amount used must the reaction mixture is agitated, thereaction time can be selected within the range of from 1 minute to 48hours.

Though the yield of methyl ethyl ketone peroxides so obtained issufliciently high to allow use of the: entire re- Iiaction productmixture as a novel oxidatively active combe maintained to avoidover-treatment and damage to color and baking quality of the flour.

The present invention employs a single composition 1 capable of bothmaturing and bleaching flours, and, in

certain embodiments, the invention is adapted to accom- The inventionhas a number of' plish maturing alone.

important advantages in additionto such flexibility of f result. ventiondoes not require such-precise control .of .the amount of oxidativelyactive material as has been neces- One primary advantage is the factthat the in- 1 position for bleaching and maturing flour, in which casewater need not be employed, the reaction product mixtures obtained asabove described are admirably suited to concentration in various Ways.First, the phase of 3 .lower specific gravity, amounting to as much as80% by volume of the total reaction product mixture, is easilyrecoverable from the higher specific gravity material, only a smallproportion of the oxidatively active products remaining in the higherspecific gravity material.

both the free water and the free methyl ethyl ketone sary with chlorinedioxide. Thus, our invention makes 1: possible the successful treatmentof flour withoutdanger of damaging the flour by overtreatment. A furthermajor i advantage of our invention is its ability to gently treat floursin a manner which may be characterized as :ac.

celerated natural aging. Another distinct'advantage of; the presentmethod is that it employs no materials which)? are deleterious tohumanbeings. Further,.the invention :1

is particularly advantageousin that it makes possible the 1adequatetreatment of flour with only a. very minimum 1:

of residual chemical agents in the flourafter treatment. In thisconnection, all embodiments of the invention involve at most theaddition of only insignificant proportions ofnon-food materials capableof surviving baking,

, and certain embodiments of the invention make it poss1-';

ble to treat the flour in such a manner that there willbe no residuewhatsoever of treating agent after baking.

In copending application Serial No. 15,783, filed concurrently herewithon behalf of Herbert O. Renner, there is disclosed a method foroxidatively treating cereal flours with certain reaction productmixtures derived from acepresent in the phase of lower specific gravitycan be removed easily without undue loss of the desired peroxidicreaction products. Finally, a highly desirable flour bleaching andmaturing product consisting essentially of i a single acyclic methylethyl ketone peroxide is obtainable from the phase of lower specificgravity by extraction with a low boiling hydrocarbon solvent such ashexane or pentane.

Advantageously, the oxidatively active materials derived'in the abovemanner from methyl ethyl ketone and hydrogen peroxide are combined witha carrier material, which can be either a finely particulate solid or aliquid. Where the carrier material is a finelyparticulatesolid;

theoxidatively active liquid reaction product mixture Y can ibe combinedwiththe solid in such proportions that'the liquid amounts to as much as25% by weightof the combined liquid and carrier. 7 p a As has beenpointedout, the phase of lower specific gravity resulting from reactionof methyl ethyl ketone 1 ;and hydrogen peroxide in the manner describedcontains,

tone and hydrogen peroxide, and with bis-(1,1" hydro- T peroxy 1,1'-methyl) 'diethyl peroxide, a major constituent of such reaction productmixtures. Copending applica tion Serial No. 822,235, filed concurrentlyherewith by Kazuo Higashiuchi, discloses that the aqueous residueremaining after extraction .of such'reaction product mixe tures with lowboiling'hydrocarbon solvents, for. example, 1 constitutes a superiorcomposition for oxidativelytreating .l

flour, such aqueous residues having a materiallygreater in addition tomethyl ethyl ketone peroxide, a substantial proportion of unreactedmethyl ethyl ketone; Thus,

about 20-40% by weight of the phase of lower specific gravity may befree methyl ethyl ketone. Advantageously, this free ketone is left inthe liquid material until after W the same has been combined with thecarrierand is then at least largely removed by volatilization. Thus,employing a particulate solid material as the carrier, the free ketonecan be removed by aerating the product, with 1 or without the aid ofreduced pressure, at a temperature not exceeding C. Assuming that arelatively large Patented July' 18, 1961 Next,

proportion of the oxidatively active liquid reaction product mixture iscombined with a solid carrier. material such as a cereal flour,especially good results are obtained by aerating with the aid of vacuumat a temperature of iO- SO, C. Ingeneral, the temperatures employedduring removal of the free methyl ethyl ketone can be increased if (1)the proportion of methyl ethyl ketone peroxides introduced to thecarrier material is relatively small or (2) the product introduced tothe carrier material contains, only small proportions of materials otherthan acyclic methyl ethyl ketone peroxides and free ketone.

While efiective flour-treating compositions can be prepared from initialreaction mixtures in which the proportion of hydrogen peroxide rangesfrom .5 to. 25 moles per mole of methyl ethyl ketone, superior resultsare obtainedjwhen the proportion of hydrogen peroxide ranges from 1 to1.5 moles per mole of ketone. Such proportions provide improved reactionrates and greater yields of methyl ethyl ketone peroxides. Within thelimits specified, increasing the relative proportion of methyl ethylketonewill increase the volume of the lower specific gravity-material,also increasing the proportion of free ketone therein, while an increasein the relative proportion of hydrogen peroxide will increase the volumeof the higher specific gravity product, also increasing the proportionof free hydrogen peroxide therein.

The rate of reaction and the yield of peroxides also depends upon theconcentration of hydrogen peroxide in the initial reaction mixture. Inthis connection, the hydrogen peroxide is preferably employed in theform of an aqueous solution containing, at least 25% by. volume.hydrogen peroxide, and considerablewater is thus introduced into thereaction mixture; While the presence ofwater is not. essential to the.reaction, it. is required in order thatthe reaction, productmixturewillseparate into phases of, lower. and higher specific gravity, thephase ofhighenspecific gravity retaining those? compounds which are. moresoluble in Water. In order to. obtainthe advantages ofphase separationand still maintain good reaction ratesand yields, the proportion ofwater in the initial reaction mixture, whetheriadded with the hydrogen"peroxide or otherwise, is kept in the range of 10-50%. by volume, based.on thegtotal reaction mixture. Thus, an aqueous hydrogen peroxidesolution should not beused which is so dilute as to provide, for theparticular proportion oi hydrogen peroxide chosen, an amount of waterlinexcess'of' 50% of the voliime of the initial reaction mixture. waterlessthan 10%. ofthevolume1of the initial reaction mixture is provided byaddition of the hydrogen peroxide 1 solution, additionaliwater should beadded to provide the minimum amount necessary for phase separation.

Thefreaction is.ratheistrongly exothermic. initially. However, if.thereaction mixture is cooled for an initial period. sufiicientto.remove the exothermic'heat, cooling canthenbe terminatedandthe reactionmixture will' remain cool forit-hebalance offthe reaction'period.

Best-yields of methyl ethyl k'etone peroxidesare obtained in theshortest reaction time when the reaction mixture is maintainedat.aitemperature within the range of l5-70 C. Within such temperaturerange, and with the proportion of hydrogen peroxide being from 1 to 1.5moles per mole of methyl ethyl ketone, the other process variables beingcontrolled as hereinb efore discussed, the phase of. lower specificgravity will amount to fror'n' 35-80% by.volume. of the reactionproductmixture', as

much as 8.0%. by weight of such lower .specijfie gravity phasebeingmethyl ethylketone peroxides, the predomii' nantportion of the organicperoxide content being an individual. acyclic methyl ethyl ketoneperoxide as "yet not completely characterized.

While the reaction proceeds at temperatures up to 100 C., the yield ofthe desired peroxides obtained ,in'aigiven reaction time decreases: as"the temperature is raisedabpve;

On the other hand, if an amount of about C. The reaction rate is alsodecreased when the, temperature of. the reaction mixture is decreasedbelow 15 C. but, by extending the reaction time, good yields can beobtained at temperatures on the order of 10 C. and lower.

Excellent e ult r ob aine by om in n the e,

While other acid catalysts can be employed, best results:

have been obtained with the. mineral acids in. amounts up to about 5% byWeight of the reaction mixture. Among the. mineral acids, the ability ofthe. acid to catalyze the reaction varies between the individual acids.Thus, while excellent reaction rates and yields are attained by using0.04-1% by weight of hydrochloric or sulfuric acid, the equivalentresults are achieved with 0.4.4 of phosphoric acid. Practical reactiontimes on the, order. of 1v minute. are provided when 1% of hydrochloricor sulfuric acidis employed and when 4.% ofi phosphoric acid isemployed. Without catalyst, the reactiontime can be extended to 48hours.

Solid, particulate, edible carriers which are suitable for preparing.compositions useful in accordance with the invention includefoodstarches, particularly corn starch, dextrines, wheat flour, defattedwheat flour, heat-treated Wheat-,fiour, pre-oxidized starches andflours, vegetable proteins, such. as wheat glutenand soybean protein,and edible. inorganic. materials, such as inorganic phosphates andcalcium sulphate, which are inertto peroxides. The particulate carriermaterial should provide a porousstructure or. a large. eifectivesurfacearea so that the oxidatively active liquid can be-retained byabsorption and/or. adsorption.

In. treating the flour, the compositions prepared in accordance with,the procedure hereinbefore" describedcan beIsprayed as liquids directlyinto the flour while are used and the carrier-supported compositionisordinarilyleft in the Hour after the oxidative treatment is completed.Therelative proportion of the oxidatively active compositions employedin accordance with the invention depends upon whether only maturing, orboth maturing and bleaching, isdesired and also upon the extent to whichmaturing or bleaching and maturing are to be. accomplished. Ordina ly,the amount of-oxidatively active-methyl ethyl ketone peroxidecomposition employed is such as to provide a hydrogenproxideobtainingmildmaturing of the flour, the hydrogen per oxideequivalentvalueiean be less than 0.001%by weight, Assuming that no additionaloxidative agents .areemployed,bleaching can beaccomplished with quantities of-theimethyl ethyl-ketone peroxide composition providinghydrogen peroxide equivalent values in the generalrange of 0;002%- to0.006% or higher, depending uponttheirat'ureof the. flour-being treated.N

E AMBLB -An initially. homogeneous. liquid reactionmixture waspreparedby blending. 25 mLaqueous hydrogen peroxide.

mint (3Z ;H2O2.b1. z n e), 50 lmethyl e y ketone nc l -lllljconcentrated sulfurieiacid. The:

t"? mat m ma e ub an ia y zit-mom; J tihe nd 1 whi b m he. a a e? Pretnd an ayers recove ed and the pro rtionof.

1 a, min tes. The

resulting liquid product wastreed' of water by means ofanhydroussodium'sulfate. By titration; theresulting product was found tohave a hydrogen peroxideequiva-- lent content of 32.6% by weight:

A.carrier-supported composition suitable for bleaching flour wasprepared by blending 40 ml. of the liquid product so obtained with 100g. of dry, food grade corn starch and drying the mixture at roomtemperature under an exhaust hood for 30 minutes. The carrier-supportedcomposition, hereinafter referred. to as composition A, wasfound tovhaveahydrogen peroxide equivalent content of 4.9% by weight. 1

To determine the relative effectiveness of the bleaching andrnaturingcomposition of this example, acontrol composition wasprepared, inaccordance with the aforementioned application Serial No. 15,783, byblending equi-molar proportions of acetone and aqueoushydrogen peroxide(60% by volume) and refluxing the. resulting liquid reaction mixtureover awater bath for one. hour, the resulting reaction product mixturebeing v intimately combined with food grade-corn SIHIClTfiS B."

carrier material. The control composition is hereinafter referred to ascomposition B.

1 Equal quantities of a commercially available; un-

bleached bread wheat flour were measured out, one quan-' tity;beingcombined with a sufficient proportion of .compo-- sition A toincorporate in the flour a hydrogen peroxide equivalent of 0.0045% byweight and theother quantity of flour being combined with a sufiicientproportion ofcompositionUBto incorporate inthe flour the same hydrogenperoxide equivalent. The two quantities of flour were 'then'allowed tostand at room temperature in closed containersand the carotene contentof the flour was measuredperiodically. The relative bleaching abilities-Of compositions A and B are plotted in the chart of FIG. 1,-.wherein itwill be noted that composition Aof this example is, at two days,approximately 100% more effective as a bleaching agent than is controlcompositionaB.

EXAMPLE 2 An initiallyhomogeneous liquid reactionmixture was. preparedby blending 57ml. of aqueous hydrogen peroxide Solution (60% H byvolume), 8915' ml. of

nietliyl etliyl'ketone and 5 ml. of 1 Nhydrochloric acid. Thereactionmixture was maintained substantially tat Iodin temperature fora periodof 30 minutes, being agitated continuously during that period by meansof aivibratingmagnetic stirrer. The resulting liquid wasneutralized-byaddition ofS ml. of 1 N sodiumhydroxide and was thenallowed to stand until ithad separated into distinct upper and lowerphases; The upperphase was recoveredby means of a separatory funnel.

Of the*recovered liquid, 50 ml. was extracted with 500 of hexane,extraction being carried out at room temperature withcontinual agitationfor 30 minutes and tlie heXane then removed under vacuum, leaving as theresidue a viscous liquid product.

A carrier-supported composition suitable for" use .in bleaching flourand the like was preparedby blending 2 g; of tlre'viscous liquid productwith g. of dry, food grade corn starch andaspirating the resultingblendfor 30 minutes atroom temperature with air to remove any remainingtraces of hexane or other volatiles. The resulting-product was found tohave a hydrogen peroxide equivalent content of 4.35 by weight, and ishereinafter referred to as composition C.

For purposes of comparison, a control composition was prepareddnaccordance with the aforementioned copendiiig-application Serial No.15,783 by blendingequimolar proportions of acetone and aqueous hydrogenper:

oxide (60% H 0 by volume) and aging over a boil ing water batlr for onehour, the resulting reaction prodi uct rtiixture then beinggextractedfive times with equal volumes of hexane, the extracts combined andthesol 'removed to provide a composition predominantlycompfisingbis'-:(l;l -hydroperoxy 1,1'-methy1) diethyl perr oxide." 1The product wasintiinately combinedwith food, grade corn starch, theresulting icomposition being herein after refeiredto"ascomposition D.

Equali samples of a commercially" available unbleached bread wheatflour'were measured out. A suflicient-prm portion of composition. C wasadded toone sample to incorporate therein a hydrogen peroxide equivalentcontentof .006%' by weight; Similarly, a sufiicient proportion ofcomposition D was blended with the other sample of flour tointroduce-therein the samehydrogen peroxide equivalent. Thetwosamples-of flour were then allowed to i stand at room temperature inclosed containers and: the carotene "content ofthe two samples wasdetermined.

from time totirne; the results beingillustrated in FIG: 2. Here, it willbe" noted thatcomposition C is vastly. su perior to composition D,providing adequatebleaching,

for commercial purposes, within a period of approximate ly two days.

In considering Examples l and 2, it; is tobe understood that theseexamples compare the' compositions of the present invention with thecorresponding compositions ofapplicationSerial No. 15,783, whichapplication discloses theonly other known oxidative agents, aside from:

chlorine dioxide, which are capable ofboth maturing and; bleaching wheattflour. In Example 1, the comparison is between compositions whichareprepared by using sub-.- stantially the entire reaction product mixture,while the comparison in Example 2 is between products each predominantlycomprising only a single peroxidic compound. In the case of compositionD of Example 2,1the:

single compound is bis-(1,1'-hydroperoxy 1,.1'-methyl) diet-hylperoxide. In the case of composition C of Example 2, the peroxidiccompound of methyl ethyl. ketone';

has not asyet beencompletely characterized.

EXAMPLE 3 To demonstrate the effect of treatment of flour in accordancewith the invention on bread baked. from. the flour, flour samples of acommercially available unbleached bread wheat flour were taken, sample 1being.

used as control with no bleaching or maturing agent added thereto, andsamples 2, 3 and 4 being treated by addition of composition A of'Example1 in proportions providing in the fioursampleshydrogen peroxideequivalent values of .003,;0045 and.006% by weight, respeo tively. Theflour samples were allowed'to stand 'inclosed containers for. 15 days atroom temperature and white bread was tlien made by preparingseparatedo-ughs from l each'flour sample by a conventional sponge-dough procedure, using. the following formula:

Sponge Ingredient; Dough;

Baked under identical conditions, the bread. from the four flour samplesscored as follows:

It is thus apparent thatthe internal-characteristics of bread preparedfrom flour treated in accordance with the invention improvedproportionately as the level of treatmentinc'reased from .003% by weightof the flour to .006%. The improvement in crumb color is that whichwould be. expected to result from bleaching of the magnitude describedwith reference to Example 1. The-improvement in loaf volume and grain isthat which would be expected to result from adequate maturing of ,thflour.

Analytical procedures Total peroxide content of the reaction productspreparedas hereinbefore described can be determined by (1) potassiumiodide-thiosulfate titration, using aqueous sulfuric acid (1 part H 80to 9 parts water by volume) or (2) modified Wheeler titration, omittingchloroform. The results are expressed as the hydrogen peroxideequivalent value.

Free hydrogen peroxide is determined as follows:

Step l.--A 0.05 g. sample of the material to be analyzed is combinedwith 25 ml. water and 1 mg. catalase and allowed to react for 30 min.Step 2.25 ml. aque ous sulfuric acid (1 part conc. H 80 to 4 parts waterby volume) is added, followed by 1 ml. saturated potassium iodidesolution. Step 3.The solution is titrated with standard thiosulfate togive the total organic peroxide content, free hydrogen peroxide havingbeen destroyed by the catalase in step 1. Step 4.-Subtract the totalorganic peroxide content, determined in step 3, from the totalpenoxidecontent, the difference being free hydrogen peroxide.

Free methyl ethyl ketone is measured as follows:

Step 1 .Combine 200 ml. of .3% fresh hydroxylamine hydrochloride and a.2 g. sample of the material to be analyzed and allow to stand for 3min. Step 2.-Titrate with standard .1 N sodium hydroxide until the pH isbrought to the original pH of the hydroxylamine hydrochloride solution.Step 3.Compute percent free methyl ethyl ketone as follows:

(Titration value) (0.00777) 100) Sample weight =percent methyl ethylketone Characterization of methyl ethyl ketone peroxide constitutingpredominant proportion of reaction product The compound titrates in thesame fashion as bis-(1,1'- hydroperoxy l,1-methyl) diethyl peroxide, thecorrespondingcompound derived from acetone.

Active oxygen was determined for the methyl ethyl ketone peroxide inquestion in the following manner: The phase of lower specific gravityproduced in accordance with Example 1 was recovered and extracted withhexane, the solvent and free ketone then being removed from the extractby fractional distillation under vacuum. The residue from thedistillation step was then dissolved in cold hexane, dried withanhydrous sodium sulfate and cooled to 70 C. on a Dry Ice-ethyl alcoholbath, causing the peroxide to be thrown down as a heavy, oily liquid.The hexane was decanted, the purified product recovered, and theprocedure repeated. The active oxygen content of the finally recovered,purified product was 8 determined by titration with .1 N thiosulfate andcomputed in accordance with the following formula:

(Titration value) (.0008) Sample Weight =Peroent active 0 by weight;

The active oxygen was found to be 22.4% by weight,

.2% less than the theoretical active oxygen content ofbis-(1,l'-hydroperoxy 1,l-ethyl) diethyl peroxide.

In similar determinations, the material thrown down from the cold hexanesolution has varied from a solid to a heavy liquid at room temperature,apparently due to the presence of varying, small amounts of impurities.

Both the active oxygen determination and the fact that the correspondingcyclic compounds are not titratable by the thiosulfate procedureindicate that the product is the acyclic dimen'c peroxide of methylethyl ketone.

We claim: H 1. The method for oxidatively treating flour to materialhaving a substantial peroxide content predominantly constituted byacyclic peroxidic reaction productsof methyl ethyl ketone and hydrogenperoxide which are titratable with thiosulfate, the proportion of saidmaterial employed providing a hydrogen peroxide equivalent value, basedon the weight of the flour, of at least about 0.001%

2. The method for oxidatively treating flourf to at least mature thesame comprising introducing into the flour a small but effectiveproportion of an oxidatively active liquid reaction product mixture,obtained by reacting methyl ethyl ketone and hydrogen peroxide at below100 C., said reaction product mixture having a substantial peroxidecontent predominantly constituted by acyclic methyl ethyl ketoneperoxide, the proportion of said reaction product mixture employedproviding a hydrogen peroxide equivalent value, based on the weight ofthe flour, of at least about 0.001%.

3. The method of claim 2 wherein said liquid reaction product mixture issupported on a particulate carrier. 4. The method of claim 3 whereinsaid carrier is a finely particulate cereal product.

5. The method for oxidatively treating flour to at least,

mature the same comprising introducing into the floura small buteifective proportion of an oxidatively active material prepared by 1)combining methyl ethyl ketone, aqueous hydrogen peroxide and 0-5% of anacid catalyst to provide an initially homogeneous liquid reactionmixture containing 1050% by volume water and 5-2.5 moles of hydrogenperoxide per mole of methyl ethyl ketone, (2) maintaining such reactionmixture below 100 C. for from 1 minute to 48 hours and thereby causingthe methyl ethyl ketone and hydrogen peroxide to react to form anacyclic methyl ethyl ketone peroxide, (3) allowing the resulting liquidreaction product mixture to separate into phases of lower and higherspecific gravity;

mature the same comprising introducing into the flour a small buteffective proportion of the acyclic peroxidic compound produced by (1)combining methyl ethyl ketone, aqueous hydrogen peroxide and '05% of anacid catalyst to provide an initially homogeneous liquid reactionmixture containing 10-50% by volume water and- .5-2.5 moles of hydrogenperoxide per mole of methylethyl ketone, (2) maintaining such reactionmixture ;be:

at lease mature the same comprising introducing into the flourj a smallbut effective proportion of an oxidatively active low 100 C. for from 1minute to 48 hours and thereby causing the methyl ethyl ketone andhydrogen peroxide to react to form an acyclic methyl ethyl ketoneperoxide, (3) allowing the resulting liquid reaction product mixture toseparate into a phase of lower specific gravity, containing said methylethyl ketone peroxide in solution, and a phase of higher specificgravity, (4) recovering said phase of lower specific gravity, and (5)extracting said methyl ethyl ketone peroxide from said recovered phase,the proportion of said acyclic peroxidic compound employed providing ahydrogen peroxide equivalent value, based on the weight of the flour, ofat least about 0.001%.

8. The method for oxidatively treating flour to at least mature the samecomprising introducing into the flour a small but effective proportionof an oxidatively active material wherein at least a material proportionof the oxidatively active content is constituted by an acyclicReferences Cited in the file of this patent UNITED STATES PATENTS1,483,546 Gelissen Feb. 12, 1924 1,539,701 Sutherland May 26, 19251,866,412 Van der Lee July 5, 1932 2,903,361 Marks Sept. 8, 1959 FOREIGNPATENTS 444,544 Great Britain Mar. 23, 1936

1. THE METHOD FOR OXIDATIVELY TREATING FLOUR TO AT LEAST MATURE THE SAMECOMPRISING INTRODUCING INTO THE FLOUR A SMALL BUT EFFECTIVE PROPORTIONOF AN OXIDATIVELY ACTIVE MATERIAL HAVING A SUBSTANTIAL PEROXIDE CONTENTPREDOMINANTLY CONSTITUED BY ACYCLIC PEROXIDIC REACTION PRODUCTS OFMETHYL ETHYL KETONE AND HYDROGEN PEROXIDE WHICH ARE TITRATABLE WITHTHIOSULFATE, THE PROPORTION OF SAID MATERIAL EMPLOYED PROVIDING AHYDROGEN PEROXIDE EQUIVALENT VALUE, BASED ON THE WEIGHT OF THE FLOUR, OFAT LEAST ABOUT 0.001%.